LYECO LY401F DOUBLE BASS REFLEX
Giovanni Militano  
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INTRODUCTION
This is my entry for the Lyeco LY401F Full Range Contest. The LY401F is a low Q driver (Qts=0.17), so one would expect that it will work well in a horn enclosure. Seeing that I don't have any experience with back loaded horn enclosures, I thought I would keep things simple and try out a double bass reflex enclosure for the LY401F.
DOUBLE BASS REFLEX ENCLOSURE
I decided to try a double bass reflex enclosure as I suspected it would provide good low frequency extension in a medium sized enclosure. To model the enclosure, I used the Quarter Wavelength Loudspeaker Design Worksheets by Martin J. King. This is my first time trying worksheets and the version I have is from 2002. The worksheets have since been upgraded. If this design is to advance beyond a contest submission, I would upgrade to the newer worksheets and tweak the enclosure dimensions. The calculated frequency response from the worksheets is shown on Figure 01 below.
Figure 01: Calculated Frequency Response - Lyeco LY401F Double Bass Reflex
The double bass reflex enclosure provides good low frequency extension, F3 ~ 50Hz and F10 ~ 42Hz. Not bad for a 4" driver.
The enclosure design for the Lyeco LY401F Double Bass Reflex is shown in Drawing 01 and the design notes are shown in Drawing 02.
Drawing 01: Lyeco LY401F Double Bass Reflex Enclosure Plan
A single driver design will likely require some baffle step correction / compensation (BSC). The amount of attenuation required will be room and amplifier dependent. About 3 to 5 dB of attenuation is a good starting point. You can use the component values shown in Drawing 02 and tune the BSC to suit your room and amplifier.
Drawing 02: Lyeco LY401F Enclosure Design Notes